This invention is generally directed to processes for the preparation of phthalocyanines, and more specifically the present invention is directed to processes for obtaining mixtures or composites of titanyl phhthalocyanine polymorphs, including Type I, Type II, Type III, Type IV, and X polymorphs, reference for example copending application U.S. Ser. No. 533,261, the disclosure of which is totally incorporated herein by reference. In U.S. Pat. No. 4,898,799, the disclosure of which is totally incorporated herein by reference, there is disclosed, for example, the preparation of selected polymorphs of titanium phthalocyanines, and layered photoconductive members comprised of the prepared phthalocyanine composities. In one embodiment, the present invention is directed to a process for the preparation of composites of titanyl phthalocyanines and vanadyl phthalocyanines by suspending the vanadyl phthalocyanine in a solvent mixture of trifluoroacetic acid and methylene chloride; adding titanyl phthalocyanine to the stirring mixture; and thereafter precipitating the desired titanyl phthalocyanine and vanadyl phthalocyanine composite by, for example, adding with stirring the aforementioned mixture to water, separating the product therefrom by, for example, filtration, and washing the composite product obtained. The term "composite" refers in an embodiment of the present invention to separate or disparate parts or components, reference for example U.S. Pat. No. 4,607,124, the disclosure of which is totally incorporated herein by reference. Generally, the composite in an embodiment of the present invention is comprised of from about 95 to about 5 weight percent of the titanyl phthalocyanine, and from about 5 to about 95 weight percent of the second phthalocyanine, and preferably from about 95/5 to about 60/40, especially with a composite comprised of titanyl phthalocyanine and vanadyl phthalocyanine or other metal, or metal free phthalocyanine. The resulting composite phthalocyanine, especially those containing the titanyl phthalocyanine polymorph IV and Type X can be selected as organic photogenerator pigments in photoresponsive imaging members containing charge transport layers such as aryl amine hole transport molecules. The aforementioned photoresponsive imaging members can be negatively charged when the photogenerating layer is situated between the hole transport layer and the substrate, or positively charged when the hole transport layer is situated between the photogenerating layer and the supporting substrate. The layered photoconductor imaging members can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic processes wherein negatively charged or positively charged images are rendered visible with toner compositions of the appropriate charge. Generally, the imaging members are sensitive in the wavelength regions of from about 700 to about 850 nanometers, thus diode lasers can be selected as the light source.
Processes for the preparation of titanyl phthalocyanine are known, however, many of them require the use of a strong acid, such as sulfuric acid, and these processes are not easily scalable; the aforementioned copending application for example. One process as illustrated in Konica Japanese Laid Open on Jan. 20, 1989 as 64-17066, the disclosure of which is totally incorporated herein by reference, involves the reaction of titanium tetrachloride and phthalodinitrile in an alpha-chloronaphthalene solvent to produce dichlorotitanium phthalocyanine, which is then subjected to hydroysis by ammonia water to enable alpha-type phthalocyanine. This phthalocyanine is preferably treated with an electron releasing solvent such as 2-ethoxyethanol, dioxane, lor N-methylpyrrolidinone, followed by subjecting the alpha-titanyl phthalocyanine to milling at a temperature of from 50.degree. to 180.degree. C. In a second method described in the aforementioned Japanese Publication, there is disclosed the preparation of alpha-type titanyl phthalocyanine with sulfuric acid. Another method for the preparation of alpha-titanyl phthalocyanine involves the addition of an aromatic hydrocarbon, such as dichlorobenzene, solvent to an aqueous suspension of the phthalocyanine, and heating, reference Japanese Laid Open 20365/1988, laid open on Jan. 28, 1988. In Japanese 171771/1986, laid open on Aug. 2, 1986, there is disclosed the purification of metalloxy phthalocyanine by treatment with N-methylpyrrolidinone. Imaging members with the above prepared prior art phthalocyanines are also known. Although the known processes are suitable for their intended purposes, there continues to be a need to provide photogenerators in which the process for preparing the desirable polymorph is scalable and simple to accomplish economically. Furthermore, there is a need to stabilize what is believed to be the excellent photoactive titanyl phthalocyanine polymorphs (Type IV and Type X) by the addition of other components whose concentration can be adjusted to achieve the appropriate balance between polymorph stability, photosensitivity, cycling lifetime, breadth of the spectral response in the IR region (to compensate for wavelength shifts on laser aging) and the like.
Generally layered photoresponsive imaging members are described in a number of U.S. patents, such as U.S. Pat. No. 4,265,900, the disclosure of which is totally incorporated herein by reference, wherein there is illustrated an imaging member comprised of a photogenerating layer, and an aryl amine hole transport layer. Examples of photogenerating layer components include trigonal selenium, metal phthalocyanines, vanadyl phthalocyanine, and metal free phthalocyanines. Additionally, there is described in U.S. Pat. No. 3,121,006 a composite xerographic photoconductive member comprised of finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. The binder materials disclosed in the '006 patent comprise a material which is incapable of transporting for any significant distance injected charge carriers generated by the photoconductive particles.
Photoresponsive imaging members with squaraine photogenerating pigments are also known, reference U.S. Pat. No. 4,415,639. In this patent, there is illustrated a photoresponsive imaging member with a substrate, a hole blocking layer, an optional adhesive interface layer, an organic photogenerating layer, a photoconductive composition capable of enhancing or reducing the intrinsic properties of the photogenerating layer, and a hole transport layer. As photoconductive compositions for the aforementioned member, there can be selected various squaraine pigments, including hydroxy squaraine compositions. Moreover, there is disclosed in U.S. Pat. No. 3,824,099 certain photosensitive hydroxy squaraine compositions.
The use of selected perylene pigments as photoconductive substances is also known. There is thus described in Hoechst European Patent Publication 0040402, DE3019326, filed May 21, 1980, the use of N,N'-disubstituted perylene-3,4,9,10-tetracarboxyldiimide pigments as photoconductive substances. Specifically, there is disclosed in this publication evaporated N,N'-bis(3-methoxypropyl)perylene-3,4,9,10-tetracarboxyldiimide dual layered negatively charged photoreceptors with improved spectral response in the wavelength region of 400 to 700 nanometers. A similar disclosure is revealed in Ernst Gunther Schlosser, Journal of Applied Photographic Engineering, Vol. 4, No. 3, page 118 (1978). There is also disclosed in U.S. Pat. No. 3,871,882 photoconductive substances comprised of specific perylene-3,4,9,10-tetracarboxylic acid derivative dyestuffs. In accordance with the teachings of this patent, the photoconductive layer is preferably formed by vapor depositing the dyestuff in a vacuum. Also, there is specifically disclosed in this patent dual layer photoreceptors with perylene-3,4,9,10-tetracarboxylic acid diimide derivatives, which have spectral response in the wavelength region of from 400 to 600 nanometers. Also, in U.S. Pat. No. 4,555,463 , the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with a chloroindinium phthalocyanine photogenerating layer. In U.S. Pat. No. 4,587,189, the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with a perylene pigment photogenerating component. Both of the aforementioned patents disclose an aryl amine component as a hole transport layer.
Moreover, there is disclosed in U.S. Pat. No. 4,419,427 electrographic recording media with a photosemiconductive double layer comprised of a first layer containing charge carrier perylene diimide producing dyes, and a second layer with one or more compounds, which are charge transporting materials when exposed to light, reference the disclosure in column 2, beginning at line 20. Also of interest with respect to this patent is the background information included in columns 1 and 2, wherein perylene dyes of the formula illustrated are presented.
Furthermore, there is illustrated in copending application U.S. Pat. No. 4,514,482, entitled Photoconductive Devices Containing Perylene Dye Compositions, the disclosure of which is totally incorporated herein by reference, an ambipolar imaging member comprised of a supporting substrate, a photoconductive layer comprised of specific perylene dyes different than the perylene pigments of the present invention, which dyes are dispersed in a polymeric resinous binder composition; and as a top layer a specific aryl amine hole transporting substance dispersed in an inactive resinous binder.
In a copending application U.S. Ser. No. 537,714, the disclosure of which is totally incorporated herein by reference, there are illustrated photoresponsive imaging members with photogenerating titanyl phthalocyanine layers, including an alpha-titanyl phthalocyanine prepared by vacuum deposition. It is indicated in this copending application that the imaging members comprised of the vacuum deposited titanyl phthalocyanines and aryl amine hole transporting compounds exhibit superior xerographic performance as low dark decay characteristics result and higher photosensitivity is generated, particularly in comparison to several prior art imaging members prepared by solution coating or spray coating, reference for example U.S. Pat. No. 4,429,029 mentioned hereinbefore.
In copending application U.S. Ser. No. 533,261, the disclosure of which is totally incorporated herein by reference, there are illustrated X, Z-1 and Z-2 titanyl phthalocyanines and processes for the preparation of titanyl phthalocyanine polymorphs, which comprises the solubilization of a titanyl phthalocyanine in a mixture of trifluoroacetic acid and methylene chloride, precipitation of the desired titanyl phthalocyanine, such as Type IV, separation by, for example, filtration, and optionally subjecting the product to washing. The product can be identified by various known means including X-ray powder diffraction, XRPD. More specifically, in one aspect the aforementioned copending application discloses a process for the preparation of titanyl phthalocyanines which comprises a process for the preparation of titanyl phthalocyanine which comprises dissolving a titanyl phthalocyanine in a solution of trifluoroacetic acid and methylene chloride; adding the resultant solution to a solvent system that will enable precipitation; and separating the desired titanyl phthalocyanine from the solution followed by an optional washing.
In a copending application U.S. Ser. No. 537,740, the disclosure of which is totally incorporated herein by reference, there is illustrated a process which comprises adding a pigment to a solution of trihaloacetic acid and toluene; adding the solution to a nonsolvent for the pigment; and separating the product from the solution.